The present invention relates to a refraction mapping technique for producing an image as if looking at an object subject to refraction. The technique may be used for example, in information equipment which includes an entertainment system such as a video game device or the like.
In a video game device, when looking at the bottom of the sea through the water surface, it looks like the bottom of the sea is distorted due to refraction. Refraction mapping is known as a method of producing a realistic picture by simulating the refraction as described above.
It is required in conventional refraction mapping for a land portion protruding from the water surface and a portion under the water to implement separately a parallel projection rendering, in a vertical direction onto the water surface, thereby making the burden on a central processing unit (CPU), a graphic processing unit (GPU) and the like to be large.